"Julian and I would like to make the movie. We're having detailed thinking about it all," Neame said. "But there's a lot to be worked out. Turning a TV show into a movie is not straightforward, it doesn't happen very often and it's not uncomplicated."

Reassembling the large ensemble cast, many of whom have moved on to other projects, is one challenge.

"That can sometimes take a while. But in principle, those of us who have given many years of our lives over to the show would be keen to do it if we could make it work," Neame said.

Fellowes, who wrote every episode of the hit PBS drama in its six seasons, would have to carve time out of his schedule. He's busy now with "The Gilded Age," NBC's series about well-heeled 19th-century Americans that's expected to debut in 2017.

Neame, as managing director of NBC Universal-owned British production company Carnival Films, has responsibilities including the TV series "The Last Kingdom."

Then there's the challenge of how to revisit the "Downton" saga. For starters, Neame said, there would be no drastic fast-forward in the lives of the aristocratic Crawley family and those who serve them. The series ended Sunday with the arrival of 1926.

"If you jump 20 years and you have the children as adults, the fans are going to watch new actors and Michelle Dockery (Lady Mary) is going to have to wear a gray wig," Neame said. "That's too far removed from what people love. So we have to give them the same characters but in a new scenario, a fresh kind of story."

Kevin Doyle, who played butler-turned-teacher Mr. Molesley, said he's discussed the possibility of a film with other cast members and found "a sort of general acceptance that it might well get made."

But, he added, "I'm not convinced it's necessary. I think the story has kind of been told. I'm not sure what more we could tell or should tell about those characters."

A movie based on a character-driven TV drama, period or not, is a true rarity. Shows that have jumped to the big screen, with mixed success, are either comedies ("Entourage," ''Sex and the City"), police or action dramas ("The Untouchables," the "Mission: Impossible" franchise) or in the sci-fi genre ("The X-Files," ''Star Trek").